The present invention relates to cooling towers and, more particularly, to tornado protected cooling towers.
Cooling towers are used for many purposes including cooling systems for nuclear power plants. It is always desirable for cooling towers to be protected so as to preclude damage from natural phenomena such as tornadoes. This is not only desirable where the cooling tower is used to cool a reactor in a nuclear power plant, but is also critical to assure safety being a regulation of the U.S. Nuclear Regulatory Commission. The regulations initially required protection against only horizontally generated missiles which conventional cooling towers could easily meet. However, cooling towers are now required to preclude damage from vertically generated missiles as well in order to more nearly assure safety by precluding damage from the effects of natural phenomena such as tornadoes.
Conventional cooling towers simply do not comply with the new missile protection regulations. It has been commonplace in the past for the fan stack to be located at the top of the cooling tower for upward vertical discharge. This has meant that the fan and fan drive equipment have been exposed to vertically generated missiles without protection of any kind. It has also meant that such missiles could enter the cooling tower through the fan stack causing damage to drift eliminators, the water distribution system, and perforate fill material. Without providing a protective cover supported by a beam structure over the top of the cooling tower, it has been difficult if not impossible to meet the regulations of the U.S. Nuclear Regulatory Commission but such protective covering for conventional cooling towers has proven to add considerable expense to the over-all system.
The regulations require structures, systems, and components important to the safety of nuclear power plants to be designed to withstand the effects of natural phenomena such as tornadoes without loss of capability to perform their safety functions. It is important for the plants to be designed so that they can be placed and maintained in a safe shut-down condition in the event of the most severe tornado that can reasonably be predicted to occur at a sight as a result of severe meteorological conditions. Protection of structures, systems, and components includes those portions of the long term emergency core cooling systems such as the cooling tower that would be required to maintain the plant in a safe condition for an extended time after a loss of coolant accident. It is imperative that the plant be protected sufficiently so that it can be placed and maintained in a cold shut-down condition generally by designing protective barriers of a type capable of precluding damage from most missile strikes. However, persons skilled in the art of cooling towers have been left with the task of developing either modifications of existing cooling towers or entirely new cooling towers capable of meeting the regulations while at the same time providing efficient, effective, and reliable operation.
While those skilled in the art have generally concentrated on providing a protective cover supported by a beam structure over a conventional cooling tower, the present invention represents a substantial departure in an entirely new cooling tower concept that not only meets government regulations for nuclear power plants but also represents an improvement over conventional cooling towers by eliminating a number of problems heretofore associated with them.